The respiratory systems of horses, cattle, hogs and poultry can be harmed by the presence of ammonia in their barns, stalls, pens and other enclosures. At high enough levels, the damage can adversely affect weight gain and feed conversion [Carr and Nicolson, 1980: “Broiler Response to three Ventilation rates, Am Soc. Arg. Eng 2:414-418]. It is therefore desirable to reduce the quantity of ammonia to which these animals are exposed.
Ammonia is formed by enzymatic hydrolysis of urea, which is present in animal waste. The hydrolysis is catalyzed by the enzyme urease, which is produced by certain microorganisms that are commonly found in animal waste. Inhibition of microbial growth through the addition of an antimicrobial agent to animal waste should therefore reduce ammonia production.
Inhibiting microbial growth is also desirable because certain microbes can directly harm animals. For example, Staphylococcus, Streptococcus and Escherichia coli bacteria cause mastitis, a disease of the mammary tissue of dairy cows. Other bacteria have been known to increase the mortality rates of poultry and reduce weight gain in other animals.
The concept of using a particulate absorbent material comprising an antimicrobial agent such as Bronopol™ is taught in the art (see Baldry et. al U.S. Pat. No. 5,109,805). The product disclosed in Baldry et al. is a small animal litter for household pets, particularly cats.
As a household pet litter, clay based absorbent materials are typically used in un-admixed form and in sufficient quantity to effectively absorb the entire volume of the pet urine into the particulate material to maintain dry conditions in the litter box. For this purpose, clay-based materials, which have good absorbency characteristics, are commonly used. In such applications, all or substantially all of the absorbed urine is brought into intimate contact with the antibacterial agent carried in or on the particulate absorbent material thereby establishing conditions favourable to significant reductions in bacterial growth in litter applications disclosed in Baldry et al.
However, large animal stall and poultry barn bedding applications are subject to vastly different conditions than those of domestic pet litter applications. In order to cope with the very large volumes of urine produced by large animals such as horses and cows, or large numbers of animals, such as poultry or hogs, absorbent stall bedding materials must be applied to the stall floor in large quantities and changed frequently. In view of cost considerations, a clay-based absorbent material such as the domestic litter disclosed in Baldry et al. is excluded as a suitable large animal stall bedding material. Instead, the bedding materials of choice for large animal stalls and poultry barns are wood shavings and/or saw dust and/or straw, which are commonly available at a relatively low price.
While Baldry et al. discloses that antibacterial agents can be incorporated into or surface treated onto a variety of other absorbent particulate materials, the cost of treating wood shavings or straw with a bactericidal agent in the manner disclosed in Baldry et al. would be prohibitive and effectively excludes such an application of the teachings of Baldry et al. to large animal stall applications.
As noted in Baldry et al. at column 2, line 64 to column 3, line 7, the presence and nature of the absorbent material exercises a considerable effect on bactericidal action, and a given bactericidal agent may be more or less effective against bacteria in urine alone or depending on the particular absorbent material of which the litter is composed. Thus, the effectiveness of anti-bacterial agents in small animal litter applications such as those disclosed in Baldry et al. is not a reliable indicator of their effectiveness in the radically different large animal stall applications. or in instances such as poultry barns where larger areas require treatments.
Therefore a need remains for a cost-effective method of employing the antimicrobial properties of known bactericidal materials to large animal stall applications.